Selection of Blasting Nozzle Length

Abrasive blast nozzles are designed to meet a wide variety of needs, and they are supplied in various lengths and configurations. Proper nozzle selection depends upon the surface to be cleaned, the size of the overall job to be done, the amount of compressed air that is available, and the type of abrasive to be used. When the air and abrasive reach the blast nozzle, the nozzle design should allow for rapid acceleration of the mixture to be evenly dispersed in a high-velocity pattern.

?Nozzle bore size is very critical to productivity. The bore diameter determines air volume requirements at given nozzle pressures as well as abrasive consumption and cleaning production rates.

?Nozzle length seems not as crucial as nozzle bore size, but it can affect the blasting force. The longer the nozzle length is, the stronger the blasting force is. When we select the nozzle length, there are three things need to consider: the accessibility of the operator to the work, the type of surface to be cleaned, and the amount of surface to be cleaned.?

Generally, a longer nozzle should be selected to achieve the most efficient for surfaces that are difficult to clean, such as rusted and pitted steel or tight mill scale. The extended nozzle length produces a venturi effect, allowing the nozzle to achieve more power. The venturi effect is produced by a narrowing of the nozzle, which increases the speed of the blast media/air mixture. So long venturi nozzles are the industry standard for blasting surfaces that are 18 to 24 inches away for hard-to-clean surfaces or 30 to 36 inches for loose paint and soft surfaces.

Due to the shorter construction, small nozzles can create this effect only to a limited extent or not at all. For this reason, short nozzles are more suitable for cleaning structures that require blasting with greater pinpoint precision or used when the surface area is small or when the cleaning job is very easy, such as raised and flaking paint.

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